The present invention relates to means for actuating a folding blade and more particularly to apparatus for use in the garment industry for creasing a fabric work piece.
In automated garment fabrication devices it is sometimes desirable to fold and crease and fabric work piece so that it then may be sewn along the folded together edges. One example of such operation is in the automated manufacture of front pockets for use in jeans. During such a procedure a facing ply is dropped onto a pocket liner, the two pieces are sewn together along one edge of the facing ply and the sewn together pieces are then folded over and the folded together edges are sewn to form the complete pocket. The pocket is later installed in the front panels of the jeans.
The folding and creasing operation is extremely difficult to carry out mechanically because the fabric work pieces are limp and have no resiliency. They therefore are difficult to grip and to position. In one prior art folding device a fabric work piece is dropped between overlying and underlying moving conveyor belts which, between them, fold over the work piece and transport it to a second location. See U.S. Pat. No. 3,669,443. In another device a movable die actually lifts the edge of the work piece, folds it over and then presses the fold to crease it. See U.S. Pat. No. 3,493,151.
Such prior art devices suffer from such various disadvantages as being incapable of exerting enough force to firmly crease the work piece or being incapable of exactly aligning the fold line on the work piece.
To crease firmly the work piece requires the application of a good deal of force, in a short period of time, and at a precisely controlled moment. These criteria have been difficult to meet with heretofore known electromechanical or pneumatic type actuators without bulky, expensive mechanisms.